FORSYTH COUNTY, Ga. -- A police officer who was waiting in the drive-thru line at a McDonald's restaurant in Forsyth County is accused of pulling a gun on the customer ahead of him because the officer was angry at having to wait for his food.

The off-duty officer is Detective Sgt. Scott Biumi, 48, of the DeKalb County Police Department. Biumi is charged with felony aggravated assault on the customer. 11Alive News was not able to reach him for comment Wednesday night.

However, we knocked on his door in Cumming on Thursday and Biumi came to the door only to tell us the name of his attorney.

We've now learned Scott Biumi will have his police certification suspended.

"This flies in the face of decency and police professionalism and you can quote me on that!" said Ken Vance, the Executive Director of Georgia's Peace Officer Standards and Training Council. "His certification will be suspended immediately."

"He put his hand right here," said the customer, 18-year-old Ryan Mash, pointing to his upper chest and shoulder area, "then he pulled the gun and put it, pointed it at, like, my neck area."

Mash is a high school senior who also works at that McDonald's, on Old Atlanta Road in south Forsyth county.

It was April 9, a Tuesday night, at 10:30.

Mash was not working that night.

He drove two friends to the McDonald's and they were in his Ford 150 pickup truck, at the head of the line, at the window, when the man they now identify as Biumi pulled up behind them in a black Chevy Impala.

"And we were waiting on them to cook the food. And the cop -- I didn't know at first that he was a cop -- pulled up behind us and waited about two minutes, two to three minutes.... And he got out and started yelling, yelling at us, 'Stop holding up the drive-thru line,' this that and the other. He walked back over to his car, got back in, and I said, 'Sorry for the inconvenience, Sir.' And he goes, 'Who has the loud mouth?' And I was, like, 'I said that,' not being smart or anything. He's like, 'Well, you never know who you're messing with.' And I was just like, 'No, Sir, I don't.' He goes, 'Keep your mouth shut.' I was like, 'I'm sorry.' He's like, 'Well, you don't know who you're messing with. And there's some crazy people out there.' And that's when he pulled the gun on me, and kept on yelling at me for about thirty more seconds. And then walked off."

Then the man got back into his car and drove away.

We got a copy of Biumi's training record. He began employment with DeKalb County Police in March of 1988. Over his 24 year history with the department he received more than 17 hundred hours of training, including a course in 2012 on 'ethics and professionalism'.

The Forsyth County Sheriff's Office incident report quotes Mash and other witnesses as recalling that Biumi said to them, "You don't know who you are [expletive]-ing with," and "You never know who you are [expletive]-ing with."

One of Mash's friends had noticed a police badge on the man's belt as the man reached into the pickup with his gun.

Mash and his friends got the tag number and description of the man's car.

McDonald's got the video.

The video shows a man in a business suit standing outside the driver's side of the vehicle that's at the drive-thru window, pulling a gun and leaning into the vehicle, pointing the gun at the driver.

Forsyth County Sheriff Duane Piper traced the man's license plate to the DeKalb County Police Department, and Biumi. Then the teens who were in the pickup truck, the Sheriff said, identified Biumi from a photo lineup. The Sheriff arrested Biumi Wednesday.

"We believe, right now, that it was his duty weapon, and a DeKalb-County-issued vehicle that he was in," Sheriff Piper said.

Piper said he does not believe that Mash and his friends did or said anything to provoke Biumi, or to make him think they might be criminal suspects endangering anyone's life. And Piper said witnesses never heard or saw Biumi identify himself as a police officer.

"Terribly disappointing," Sheriff Piper said. "It's a betrayal of a trust to the public. We're expected to handle ourselves correctly in high-stress situations, and it's very disappointing that an officer would snap like this. It's a break in judgement that can't be excused."

"I was scared, I was very scared," Mash said. "For sure, I didn't want to die that night." He chucked for a moment, then quickly got serious again. "I didn't know what he was doing. So I stuck my hands up and said, 'I'm sorry, Sir. I don't want any problems.' And he's like, 'Okay, then. Then watch who you're talking with.' And then walked off."

Forsyth County Sheriff's deputies arrested Biumi in DeKalb County Wednesday morning, and booked him in the Forsyth County jail.

Biumi was released from the jail Wednesday afternoon on a $22,000 bond.

DeKalb County Police Chief Cedric Alexander placed Biumi on administrative leave with pay while the case is investigated.

Chief Alexander said Biumi has been on the force for more than 20 years.

"I'm just not going to stand for any behavior that goes outside that of the scope of the law," Chief Alexander said Wednesday, quickly adding, "we have to remember these are allegations that are being investigated" and Biumi is presumed innocent.

Alexander said Biumi never told his superiors about the allegations from last week. Alexander said he learned about them only when investigators from Forsyth County contacted DeKalb about Biumi.

"I'm always respectful with the cops, and they're always respectful back to me," Mash said. "And I look at them the same way now.... [But] I think he should have his gun revoked, and his badge. He shouldn't be serving in our community, because you never know, he could get angry at somebody for speeding, and pull a gun on him."

And Mash said if he could speak directly with Biumi, he'd try again to convince him he wasn't talking back to him. "I would tell him that I wasn't being a smart-ass to him."

According to the Vance, regardless of the criminal proceedings, a POST review could result in revocation of his certification.